1. Field of the Invention
The present invention is in the field of motorized wheel chairs, particularly, separable apparatuses attachable to standard wheel chairs to provide power to drive them.
2. Related Art
Substantial obstacles to mobility and everyday tasks of living continue for those disabled and bound to wheel chairs. There is a continuing need to make mobility for the wheel chair bound more reliable and convenient.
Motor drives for standard wheel chairs exist in the prior art. U.S. Pat. No. 5,494,126 to Meeker and U.S. Pat. No. 5,050,695 to Kleinwolterink Jr. describe motor drive units that may be attached to standard push wheel chairs.
U.S. Pat. No. 5,050,695 describes a geared brush type DC motor chain coupled to a very small drive wheel. It makes use of a fixed steering column. Only the height of the column can be adjusted to fit individual needs, by loosening a setscrew. The drive wheel is coupled to a frame though a bearing journal. The frame forms a well into which two large batteries are supported. Power is applied to the motor through a cable and is controlled with the control box at the top of the steering column. The speed and direction of the motor is accomplished through wings attached to the control box. The wings are attached to simple switches inside the control box. The patent further describes pivotal frames attached to the rear section of the wheel chair frame. Attached to the pivotal frames are sockets into which an inverted U-shaped crossbar is inserted. When the unit is connected to the wheel chair, two hooks on the rear of the frame hook onto the U-shaped crossbar, which lifts the rear of the frame. Two rails on each side of the frame come in contact with the X-frame of the wheel chair and this lifts the front of the wheel chair. This procedure locks the unit in place.
U.S. Pat. No. 5,494,126 describes an apparatus and method for attaching a motorized wheel to a wheel chair. This unit is attached to the front of the wheel chair through the use of two brackets bolted to the front tubes of the wheel chair. The steering column is telescopically connected to the drive wheel and held in place with a collar and a setscrew. When connecting the drive unit to the wheel chair the steering column is replaced with a temporary installation handle. After the installation handle has been inserted it is held in place with a collar and set screw. The unit is then held in a partially upright position and two posts are guided into the C shaped openings of the brackets on either side of the front of the wheel chair. The occupant then presses forward on the installation handle forcing the drive wheel back under the front of the wheel chair. After the drive wheel is all the way under the front of the wheel chair the operator must then hold it in place and slide two pins into the brackets on either side of the wheel chair. These locking pins are then held in place with locking screws. The operator must then loosen the setscrews holding the installation handle in place, remove the installation handle and then install the battery. Next replace the steering column and lock the steering column in place with a collar and setscrew. Two, wires with spade lugs must then be connected to the battery with terminal screws. It is possible to connect the wires backwards.
These devices are cumbersome in their operation, installation and transportation. The units are heavy and do not disassemble or collapse into a compact package. This creates difficulty in packing, as for example in the trunk of an automobile. Weight represents a substantial hardship, particularly for the elderly person, whose caregiver is commonly an elderly spouse. Prior art devices are also bulky and do not collapse into a small enough package for convenient transportation, again as in the trunk of a car.
The prior art units do not have batteries that are easily removable. Moreover, the batteries are not encased in a separate housing. Accordingly, separate packaging of the batteries is required to transport prior art batteries on public transportation such as commercial airlines. There is no provision for re-charging the batteries.
The prior art devices have in common a vertical shaft for holding a control module where the wheel chair occupant may reach it. This shaft is not movable, and accordingly obstructs ingress and egress from the wheel chair. The unadjustable vertical control shaft makes simple tasks difficult, such as pulling the chair up to the table, as for reading or a meal.
These units are also difficult to install for a caregiver. They are prohibitively difficult for the disabled individual themselves to install. This is due to the mounting apparatus, which cannot automatically seat itself by simple engagement with the chair, which has no alignment guides to ease installment and which also prevents folding the chair up for storage when the apparatus is attached.
The prior art devices have inefficient drive trains that use drive chains and further necessitate inefficient gearing and small drive wheels. Their systems are only 35% efficient. This inefficiency leads to a choice between either large, heavy batteries or smaller batteries that use an inordinate amount of power with an appreciably shorter charge life.
In operation, the prior art units use small drive wheels that too readily transfer shock from minor impediments, such as a brick floor. Even slightly larger objects, such as a cobble stone street, become virtually impossible to traverse.
It is in view of the above referenced shortcomings that the present invention was developed.